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“Friends” on Instant Messaging（即时通讯）
In the past, most people communicated (communicate) by phone or letter. Not many people had____41 __ (hear)of e-mail or Instant Messaging (IM). Today, many ___42___ (adult) send e-mails as their primary means of communication. Teenagers spend much of their time___43___ (use) IM to chat in real time.
With access to billions of people, the meaning of a "friend" has___44____(change). Online friends are often people that teenagers don't know in their real life. They may be people that teenagers met online by chance.
Such a relationship lacks real-life investment in a ___45___ (friend). Online friends don't ____46___ (real)know about one another. Therefore, these "friends" are more likely to be___47___ (kind). Furthermore, teenagers can ___48___(easy)be fooled. As a result, people who are ___49___ (hide)their real purpose are___50___ (increasing) targeting teenagers.